TIME INTERVAL METER AND METHOD OF ITS CALIBRATION

摘要

The meter measures time intervals between normalized start-pulses and light stop-pulses varied in amplitude. For example, such stop-pulses are typical for satellite laser ranging where reflected light pulses have considerable variation of amplitudes. Delays of these pulses in optoelectronic converter (2) and timing unit (4) depend on the amplitude of their input signals, increasing the error of time interval measurement. The current error can be defined and compensated for the end-result of time interval measurement by fixing this dependence (during calibration of the instrument) and measuring the current amplitude of stop-pulses. Adder (8) performs the compensation by subtraction of correction codes from codes of time-to digital converter (7). Such calibration prevents influence of amplitude variation for both electrical stop-pulses and light stop-pulses. During the calibration the stop-pulse amplitudes are varied continuously. That increases precision of definition of digital correction table. Filtering of data accumulated during calibration suppresses influence of noise bursts and also increases the precision. 2